Divided channel telegraph system



Nov. 8, 1949 M. POTTS DIVIDED CHANNEL TELEGRAPH SYSTEM 6 Sheets-Sheet 1 Filed June 4, 1947 9 L 7 6 2 8 2 3 2 6 8 2 L 2 6 an L L .nlv. H 2 a a a 7 a 7 n. 2 n u 2 m (1 7 W 2 w JG o l u a u w e 8 l. I j

FIG. I

R w T 3 AC n me D 7 n NT O OP C W WT L R A M ATTORNEY NOV. 8, 194-9 Ts 2,487,178

DIVIDED CHANNEL TELEGRAPH SYSTEM Filed June 4, 1947 6 Sheets-Sheet 2 FIG. 2

INVENTOR LOUIS M. POTTS, DECEASED MARTHA w. G. POTTS, EXECUTRIX TTORNEY Nov. 8, 1949 L. M. POTTS 2, 7, 78

DIVIDED CHANNEL TELEGRAPH SYSTEM Filed June 4, 1947 6 Sheets-Sheet 5 FIG. 3

ATTORNEY Nov. 8, 1949 L. M. POTTS 3 DIVIDED CHANNEL TELEGRAPH SYSTEM Filed June 4. 1947 6 Sheets-Shee t 4 INVENTOR LOUIS M. POTTS, DECEASED MARTHA w. c. POTTS, EXECUTRIX FIG. 4-4 BY ATTORNEY Nov. 8, 1949 L. M. POTTS 2,487, 78

DIVIDED CHANNEL TELEGRAPH SYSTEM Filed June 4, 1947 -6 Sheets-Sheet 5 za-l TORNEY Nov. 8, 1949 L. POTTS 'DiVIDED CHANNEL TELEGRAPH Filed June 4, 1947 6 Sheets-Sheet 6 Patented Nov. 8, 1949 DIVIDED CHANNEL TELEGRAPH SYSTEM Louis M. Potts, deceased, late of Evanston, 111., by Martha W. C. Potts, executrix, Evanston, 111., assignor to Teletype Corporation, Chicago, 111., a corporation of Delaware Application June 4, 1947, Serial No. 752,513

15 Claims.

This invention relates to telegraph systems and particularly to a divided channel system wherein a plurality of active stations may equally share line time over a channel.

An object of the present invention is to provide a divided channel system of telegraphy wherein a plurality of active stations at one end of the channel may equally share line time to transmit signals to related stations at the other end of the channel.

Another object of the invention is to provide a divided channel system of telegraphy having a plurality of stations at each end of a channel, and in which any of said stations may start or cease transmission and yet enable all active stations to share line time equally over the channel.

A further object of the invention is to provide in a divided channel system of telegraphy a first switching center automatically conditioned according to the active or idle condition of a plurality of transmitting stations associated therewith and a second switching center which automatically receives a routing signal from said first switching center Whenever a change in the traffic pattern takes place to automatically select only receiving stations for operation which correspond to active transmitting stations.

Another object of the invention is to provide a telegraph station selection system operable in accordance with the individual impulses of a signal code combination.

A further object of the invention is to provide a two-way divided channel system of telegraphy having a plurality of stations at each end of a channel, each equipped with a transmitter and a receiver, and a duplex circuit which permits simultaneous transmission ofsignals in opposite directions on the channel and half duplex operation between related stations at each end of the channel. I .-Other objects, features, and advantages of the invention,- while not specifically recited above, will appear as the description of the invention progresses.

In one embodiment of the invention, a oneway transmission system is utilized wherein three transmitting stations sequentially share line time when active, code combination by code combination, to transmit signals to three corresponding receiving stations. When a particular transmitting station starts orceases transmitting, a taut tape switch is operated which automatically conditions a first sequence switch to enable only active transmitting stations to share the channel time. The sequence switch has four stopping positions, one for each transmitting station and one for sending a routing signal whenever a change in the traffic pattern occurs. When a transmitting station is idle, its position is skipped by the sequence switch. The routing signal is transmitted by an auxiliary transmitter after a blank or all-spacing signal is first transmitted to condition a single magnet selector associated with a second sequence switch for operation. On receipt of the routing signal by the single magnet selector, the second sequence switch is conditioned in a similar manner to the first sequence switch so that only receiving stations which correspond to active transmitting stations are chosen for operation. The second sequence switch also has four stopping positions, one relative to each of the three receiving stations and the other in which the routing signal is received. When a transmitting station is idle, the stopping position of its related receiving station is skipped by the sequence switch.

A second embodiment of the invention relates to a two-way divided channel system using a duplex circuit. The stations at each end of the channel are equipped with both a transmitter and a receiver so that transmission may take place in either direction, but in only one direction at a time between related stations. However, the duplexing circuit will permit simultaneous transmission of messages in opposite directions if the signals are from unrelated stations. For example, one station may send signals to its related station in one direction, while another station may simultaneously send signals in the opposite direction to its related station. Thus, the system operates as a ful1 duplex on the main line and as a half duplex system between related stations. In this embodiment of the invention two sets of sequence switches are used in conjunction with the duplex circuit to accomplish two-way transmission.

A more complete understanding of the invention may be had by reference to the description which follows, when read with reference to the drawings, wherein:

Fig. 1 is a circuit illustration of three transmitting sttaions utilized in the present invention;

Figs. 2 and 3 comprise a schematic circuit illustration of a west switching center which forms part of the present invention;

Fig. 4 is a circuit illustration of an east switching center;

Fig. 4a illustrates how the sheets are arranged 3 in accordance with the first embodiment of the invention;

Fig. 5 is a circuit illustration of three transmitting stations utilized in a second embodiment of the invention; and

Fig. 6 shows how the sheets are arranged for the second embodiment of the invention and also particularly illustrates a duplex circuit utilized in this embodiment of the invention.

Referring now to the drawings the first embodiment of the invention will be described. with reference to Figs. 1 to 4, inclusive. In Fig. 1 there is indicated three transmitting stations I0, II, I2, which are designed to transmit five unit start-stop signals to remotely located receiving stations I3, I4, I6 (Fig. 4). A west switching center is disclosed in Figs. 2 and 3, while Fig. 4.

discloses an east switching center.

Each of the transmitting stations IO, M, I2, is equipped with a tape transmitter which includes a taut tape switch l1. When a. loop of tape I 8 is loose, it is an indication that the transmitter with which it is associated is transmitting or ready to resume transmitting after it has been idle, and contact tongue I9 is permitted to remain against its upper contact. When the loop of tape I8 becomes taut, the transmitter becomes idle as taut tape switch I! operates contact tongue I9 against its lower contact. Associated with each transmitter is a cam 22 which operates in each rotation of a constantly rotating cam sleeve 2| to close pulsing contact 23 and thereby provides an impulse for either winding of a polar relay 24 extending through contact tongue I9. Polar relay 24 is of the type which remains in its last assumed condition. When contact tongue I9 is against its upper contact, tongue 26 of polar relay is operated to its closed position. When contact tongue I9 is against its lower contact, tongue 26 is operated to its open position. With tongue 26 closed the circuit for a start magnet 21 of transmitting station I 0, for example, is as follows: From ground through the winding of start magnet 21, over lead 28-I, through resistance 29, through the left-hand winding of control relay 38 and in parallel with a circuit extending through the right-hand winding of control relay 30, over lead 32, through contact 33 operable by cam 34 of a sequence switch 36, over lead 31, through closed contact 36 operable by cam 39 of a regenerative repeater indicated generally at 4|, to battery 42. A regenerative repeater suitable for use in the present system is shown in the patent of W. J. Zenner et al., No. 2,105,173.

It should be mentioned at this time that sequence switch 36 may be stopped in four different positions. When magnet 43 is de-energized, its armature 44 may move to a position to engage stop 46 of cam 4! carried by sequence switch sleeve 48. This is the routing position in which an auxiliary transmitter 49 at the west switching center may send routing signals as will later appear. Magnets 5I, 52, and 53, when de-energized, function to stop sleeve 48 in a similar manner. Magnet 5! operates to stop sleeve 48 in the position shown, in which transmitter I0. when active, may transmit signals over lead 54 to regenerative repeater magnet 56 associated with regenerative repeater 4|. Similarly, operation of magnets 52 and 53 will enable transmitting stations I! and I2, respectively, when active, to transmit signals over lead 54 to regenerative repeater magnet 56. When all the transmitting stations are operating andsharing the channel, relay 43 is held energized and the routing position is skipped.

Returning now to the description of the operation of transmitter II], which it will be assumed has slack tape and is ready to transmit, it is observable that when magnet 5| is de-energized, start magnet 21 is energized over the circuit previously described. It was also noted that with magnet 5| de-energized and the sequence switch 36in the position shown in Fig. 3, both windings of relay 30 are carrying current. The windings of relay 30 oppose one another when carrying current, but the left-hand winding has more turns than the right-hand winding. Relay 30 is a polarized relay and will stay in the position last assumed. If current flows only in the right-hand winding, tongues I3I and I32 are attracted and close circuit paths later to be described. The transmitting circuit for transmitting station It) now extends as follows: From ground, through transmitting contacts 6 I, over lead 62-I, through make-before-break contact 63, now closed by cam 34 of sequence switch 36, over leads 64 and 54 and through the winding of regenerative repeater magnet 56 to battery 66. Cam sleeve 61 of regenerative repeater M is now released in conventional fashion and regenerative repeater contact 68 acts to send signals over line 69 to regenerative repeater magnet ll of a. regenerative repeater 12 located at the east switching center. Regenerative repeater 12 may also be similar to the regenerative repeater shown in the aforementioned Zenner patent. At this time, a sequence switch I3 at the east switching center will be in the position shown in Fig. 4, so that signals repeated by regenerative repeater contact I4 will be repeated over lead I6 through contact ll operable by cam 18 mounted on sleeve 19, over lead al to receiving station I3. Thus, transmitting station It at this time will transmit a single code combination to receiving station I3.

Towards the end of a single revolution of sleeve 61 of regenerative repeater M at the west switch ing center, cam 82 will close contact 83 and a circuit will be established for magnet SI of sequence switch 36 as follows: From battery 84, through the winding of magnet 5|, over lead 86, through contact 81, now closed by cam 34, over lead 88, through closed contact 83 to ground. Thus, sequence switch 36 is now released and sleeve 48 moves toward its next stopping position. Similarly, toward the end of the revolution of cam sleeve 89 of regenerative repeater I2, cam 9I will close contact 92 and a circuit will be established for magnet 94 as follows: From ground, through closed contact 92, over leads 91, 98, through contact 99 operable by cam I8, over lead IOI and through the winding of magnet 94 to battery'IUZ. Thus, sequence switch 13 at the east switching center is also released, and sleeve 19 also moves toward its next stopping position.

If it is assumed now that the tape loops I8 at transmitting stations II and I2 are also slack, sequence switch 36 at the west switching center 'will next be stopped by the armature of magnet 52 and the armature of magnet 95 stops the sequence switch I3 in a corresponding position and a code combination is transmitted from transmitting station II to receiving station 14. After this code combination has been so transmitted, magnets 52 and 95 will become energized, as was described in connection with magnets 5| and 94, to release their respective sequence switches. The armaturesof magnets 53 and 96 will now stop their respective sequence switches in positions so that a single. code combination may be transmitted from transmitthree transmitters I0, II, and I2 will sequentially share line time as long as they are in condition to transmit signals. At this time, magnet 43 associated with sequence switch 36, and mag net 93 associated with sequence switch 13, will remain de-energized and the routing position will be skipped by both of said sequence switches.

A description will now be undertaken of a mechanism at the east switching center which responds to an all-spacing signal to prepare a single magnet selector I06 for the subsequent receipt of a routing signal, as will later be described. The single magnet selector may be of the type shown in the patent of Krum, No. 1,745,633. Mounted on cam sleeve 89 of regenerative repeater 12 are a pair of cams I03, I04. Pivoted at I01, is a lever I08 which has a vertically extending arm I09 and a shorter horizontally extending arm III. The vertically extending arm I09 is provided with a groove H2 and with a projection II3 which follows the periphery of cam I04, as spring II5 draws lever I'08 in a counterclockwise direction. In response to marking impulses, an extension III) of regenerative repeater contact 14 moves upwardly in line with the groove II2 of lever I08, so that projection II3 may move into the notches II4 of cam I04 and allow lever I08 to pivot slightly in a counterclockwise direction for a purpose which will later appear.

About the common pivot II6 are mounted the levers H8 and I I9. Lever I I8 is provided with a projection I2I which pursues the periphery of cam I 03 under tension of spring I20. Pivotally mounted at I22 on lever H9 is a lever I23 which is urged in an upward direction by spring I24. If an all-spacing signal is received, extension I I0 of repeater contact 14 will not move in alignment with groove II2 of lever I08, so that lever I08 will be held in the position shown. Under this condition, at the end of a revolution, cam I03 by means of its high part I26 will move against projection I2I of lever H8 and cause lever M8 to engage shoulder I21 of lever I23 to move the latter lever to the left, thereby closing contact I28. However, if any of the impulses of a code combination are markin projection I I3 of lever I08 will move into a notch II4 of cam I04 and thereby enables lever I08 to pivot counterclockwise and by means of its arm III to move lever I23 in a clockwise direction, so that shoulder I21 of lever I23 moves under the end of lever 8. Now, as lever II8 moves to the left at the end of a revolution of cam I 03, as explained, it is ineffectual to close contact I 28. It should be pointed out that when cam I03 starts to rotate, extension I2I of lever I'I8 will ride out of notch I29 to a higher part of cam I03, but this movement is insuflicient to cause closure of contact Before entering upon a description of what happens when a change occurs in the traiiic pattern, it will be understood that control relays 30, 40, and 50 and their respective companion control relays 35, 45, and 55 operate in a similar manner, so that a description of the operation of relays 30 and 35, which are related to station I0 will suflice for the other relays. Operation of control relay 30 has been partially described above. Now, it will be assumed that the loop of tape I8 at station I0 becomes taut and contact tongue I9 is moved against its lower contact. Upon the next revolution of constantly rotating cam sleeve 2I, cam -22 will close contact 23 and polar relay 24 will operate to move its tongue 26 to its open position. Thus, the initially described circuit for start magnet 21 can no longer be completed. Stations II and I2 will operate in turn and when the position of station I0 is reached by sequence switch 36, relay 30 will be operated, since its left-hand winding does not now receive current through tongue 26 of polar relay 24. The transmitter I0 is not released because a start magnet 21 cannot operate with tongue 26 of polar relay 24 open. However, station I0 at this time will transmit its last code combination prior to assuming an idle condition.

As relay 30 operates, it pulls up its contact tongues I'3I and I32 and a main control relay I33 is energized over the following circuit: From battery I 34, through the left-hand winding of main control relay I33, over leads I36, I31, through tongue I38 (now on its back contact) of control relay 35, over lead I39, through tongue I3I (now on its front contact) of control relay 30, and over leads I41, I42, to ground. With relay I33 operated, a circuit is broken to the normal energized magnet 43 which controls the routing position of sequence switch 36. This circuit was previously made through contact tongue I 43 of relay I33 as follows: From battery I44, through the winding of magnet 43, over lead I46 through tongue I43 and its back contact, over lead I 50 and through contact I60 controlled by cam I'10 of transmitter 49. Armature 44 of relay 43 will now fall into the path of pro jection 46 of cam 41. Thus, after stations II and I2 have transmitted their next code combinations, sequence switch 36 will stop in the routing position. When contact tongue I43, of control relay I33, moved against its front contact,

relay I33 locked up over a, circuit extending over lead I50 through contact I60 operable by cam I10 of auxiliary transmitter 49.

As sequence switch 36 stops in its routing posi-- tion, the high part of cam I5I will cause contacts I52, I53, and I54 to close. Closure of contact I52 places transmitter 49 in circuit with repeater magnet 56 of regenerative repeater 4| by joining lead 54 with lead I56. The remainder of this circuit will be traced later. Closure of contact I53 provides a circuit for start magnet I51 of transmitter 49 as follows: From battery 42, through contact 38, over lead 31, through contact I 53, over lead I58 and through the winding of magnet I 51. It will be understood that magnet I51 is operated only when magnet 43 stops the sequenceswitch 36 in its routing position. In other words, when the high part of cam 48 moves rapidly past this position, magnet I51 may receive a pulse, but this pulse is not long enough to operate magnet I51. Sleeve I59 of transmitter 49 will, therefore, be released at this time, and. contact I6I will send a start impulse followed by an allspacing signal to repeater magnet 56 in the first half-revolution of cam sleeve I59. Contact I62 will then send a marking stop impulse followed by a start impulse. On the second half of the rotation of cm sleeve I59, the routing. signal will be transmitted, as will immediately hereinafter appear.

As sleeve I59 of transmitter 49 starts to rotate, cam I69 operates make-beiore-break contact I48 providing ground over lead I45 through tongue I32 of relay 39 and over lead I59 to operate the right-hand winding of relay 35. Control relay 35 operates at this time, and now looks up through its contact tongue I65 over leadsI80, I41,

and through make-beiore-break contact I48 controlled by cam I69.

With control relay energized, its tongues I38, I63, I64, and I65 (already described) are attracted. Closure of tongue I64 establishes a circuit for transmitting contact I61--I of transmitter 49 which extends to repeater magnet 56 of regenerative repeater AI as follows: From ground, over lead I66, through tongue I64 (now closed) through transmitting contact I61-I when it is permitted to move toward the low part of cam I68--I, over lead I58, through contact I52 and over lead 54 to the winding of repeater relay 56. In the second half revolution of sleeve I59, transmitter 49 functions to send a routing signal which under the assumed condition is with the first element of the code combination marking and the remainder spacing. This is due to the fact that contact tongues I64 of control relays and are open at this time and transmitting contacts I612 and I61--3 send spacing signals. Furthermore, only three transmitters are used to illustrate the invention, but the invention may have a capacity of five transmitters as illustrated. Transmitting cams I68-4 and I68-5 are not, therefore, used but would operate associated transmitting contacts, if a five station arrangement were used.

When the high part of cam I18 at the end of rotation of cam sleeve I59 operates, contact I will open and the locking circuit for main control relay I33 will be broken. Thus, tongue I43 of relay I33 may again complete a circuit for routing magnet 43 and the cam sleeve 48 of sequence switch 36 may move to a position to be stopped by the armature of magnet 52 related to transmitting station II. This is made possible since magnet 52 is now held energized as follows: From grounded lead III, through contact tongue I63, over leads I12 and 86, and through the winding of magnet 5I to battery. It is, therefore, apparent that under the assumed condition, transmitting stations II and I2 will now share the line time equally since the position of transmitting station I0 is now skipped by sequence switch 36.

What takes place when the blank signal followed by the routing signal is received at the east switching center (Fig. 4) will now be explained. It has been previously described how contact I28 is closed upon receipt of an all-spacing signal. As the all-spacing signal is received by regenerative repeater 12, at the end of the signal, contact I28 will close and cam 9I will close contact 92 to provide an obvious circuit over leads I13 and I14 for the left-hand winding of relay I16. As relay 1 I16 ope ates, it pulls up its contact tongues I11, I18, I19, II, and I82. Closure of tongue I11 makes an obvious circuit extending over lead II'II for magnet 94, while closure of tongues I18, I19 makes similar obvious circuits extending over leads I83 and I84 for magnets 95 and 96, respectively. As tongue I82 of relay I16 opens, an obvious circuit extending over lead I86 is broken for routing magnet 93. Thus, regardless of the position of sequence switch 13, it will step to the routing position to be stopped by the armature of routing magnet 93, since the armatures of magnets 94, 95, and 96 are attracted at this time. When relay I16 operated, it locked up from battery through its right-hand winding, through tongue I8I, over lead I98, through contact I81, controlled by cam I88 carried by sleeve I89 of the single magnet selector I06 to ground.

With sequence switch 13 stopped in its routing position, make-before-break contact I9I, which has been holding battery current from battery I92 over lead I94 for selector magnet I93, now places the regenerative repeater contact 14 of regenerative repeater'12 in series with selector magnet. I93 and thus swords I96-I', I96--2, I96-3 will be set in position according to the incoming routing signal. Accordingly, levers I91-I, I91--'2, and I913 which control contacts I96I, I98-2, and I98-3 will be operated. Under the assumed condition, the routing signal is marking, followed by four spacing impulses, and, therefore, contact I99--I will close While contacts I 98-4 and I98-3 will open. Since the fourth and fifth impulses are not used, no contacts are provided therefor but such contacts could be used if five receiving stations were used in conjunction with five transmitting stations.

Closure'of contact I98-I provides a circui for magnet 94 as follows: From ground, over lead 20I, through contact I 98I, over leads 282 and IOI and through the winding of magnet 94. Thus, receiver I3 will not now receive any signals since its position will now be skipped by sequence switch 13, which is again freed for movement as the high part of cam I88 opens contact tongue I81 after the routing signal is received. This breaks the locking circuit for relay I16 extending over lead I98 and as its contact tongue I82 falls away, the circuit for routing magnet 93 isagain established freeing the sequence switch 13 as just indicated above. Single magnet selector I96 will not operate again until another routing signal is received. During this time contacts I98 -I, I98-2 and I98--3 will remain in their last operated positions. Thus, under the assumed condition, transmitting stations II and I2 will send signals to receiving stations I4 and I6.

It will now be assumed that the tape loop I8 of transmitting station I0 becomes loose indicating that it is ready to resume transmission. When this occurs, closure of pulsing contact 23 by constantly rotating cam 22 causes polar relay 24 to operate and move contact tongue 26 to its closed position. Now, as the high part of cam 34 closes contact 33,:both windings of control. relay 39 are operated, and its contact tongues I3I and I32 fall away. As contact tongue I3I falls away, main control relay I33 is now operated through its left-- hand winding as follows: From battery I34, through the left-hand winding of main control relay I33, overload I36, through contact tongue I38 (still against its front contact) and over leads I4I-, I42 to ground. Thus, again a routing operation is initiated as before by the operation of main control relay I33, so that after stations II and I2 send their code combinations, sequence switch 36 stops in its routing position. However, after sending the blank signal, a second blank routing signal will now be-transmittedby transmitter 49 as contact I64 of control relay 35 is now open. This is due to the fact that as cam sleeve I 59- of transmitter 49 starts to rotate, makebefore-break contact I48 is opened by cam I69 opening the locking circuit for the left-hand winding of control relay 35. A new circuit for control relay 35 cannot be made at this time, since tongue I32 of control relay 38 is now open. Opening of contact tongue I63 of control relas 35 opens the holding circuit for magnet 5I', allowing sequence switch 36 to be again stopped for transmission of signals by station III. The receipt-of two blank signals in succession by repeating relay 1I will not cause a reoperation of relay I16, since contact I81 is timedwto open just as contact I28 closes. While the circuit has tion of transmitting station |0, stations II and |2 become associated with, or are dropped from the channel in exactly the same manner.

L n order to make sure that the sequence switches are operated in an identical manner, a periodic routin signal is automatically transmitted by operation of a counting device, indicated generally as numeral 205, which will now be described. Each time regenerative repeater 4| operates to transmit a character, cam 39 causes a lever 200 to rock about its pivot 20'! and causes stepping pawl 208, which is pivotally carried at 209 by lever 206, to step ratchet 2|| one position in a clockwise direction. Ratchet 2| is mounted on a sleeve 2|2 carried by a shaft 2|3. Suitably mounted on sleeve 2 is a drum wound spring (not shown). For preventing retrograde movement of ratchet 2| I, a projection 2|4 is provided on an arm 2|6 of armature 2", which is pivoted at 2|8. After a number of characters are transmitted, a cam 2 l9 carried on sleeve 2|2 is moved to a position to close contact 22| and thereby provide a circuit over lead 222 for main control relay I33. Control relay I33 by operation of its contact tongue 223 provides an obvious circuit over lead 224 for magnet 226. As magnet 220 operates, it attracts armature 2|I about pivot 2|8 against the influence of spring 221, thereby lifting projection 2|4 from the teeth of ratchet 2| l, which is now rotated counterclockwise to its zero position by the drum wound spring. As ratchet 2 reaches its zero position, a stop 228 carried thereby strikes arm 229 of armature 2|1. Thus, a blank signal followed by a routing signal will now be transmitted automatically, exactly as previously described. Ratchet 2| will be again stepped in a clockwise direction until a change in the trafiic pattern occurs, or until contact 22| is closed by cam 2 9, since magnet 226 may operate whenever contact tongue 223 is attracted by main control relay I33. It is to be understood.

that follower 23| will not ride fully up the high part of cam 2|9 when closing contact 22|, so that its hook portion will also assist stop 228 in halting sleeve 2|2 in its zero position.

With the drawings arranged according to Fig. 6, a second embodiment of the invention will now be described wherein a divided channel system may be used for two-way communication. It will be noted that in this system, Fig. 5 is substituted for Fig. 1 and Figs. 2, 3, 4, and 5 are each used twice so that the circuit arrangements provided therein may provide said two-way communication over a duplexing circuit indicated generally as numeral 30|. Such communication may take place between stations |W, HW and |2W and related stations ME, ME and |2E.

It will be understood that although communi cation between |0W and |0E will now be described that the remaining stations will operate in. an identical manner. In Fig. a printer receiver magnet 302 is now placed in series with lead 62-| function exactly asin the first embodiment of the invention to send signals over lead 62--| through make-before-break contact 303 to newly added lead 62--|A which extends into Fig. 2 in a manner similar to lead 62-| shown in the first embodiment of the invention. The transmitted signal will be repeated by regenerative repeater contact '68 exactly as before but lead 69W .(equivalent to previously described lead, 69) will now connect with a circuit which extends over line 3| 2 of duplexing circuit 30| to operate polar relay 3|3E. Lead 69E, extending from the opposite direction will similarly enable the operation of polar relay 3|3W. Thus, when signals are transmitted from west to east, contact tongue 3|6E of polar relay 3|3E will repeat the signals over lead 3|4E to repeater magnet H of regenerative repeater '12 in Fig. 4 of the east terminal. When signals are transmitted from east to west, contact tongue 3|6W of polar relay 3|3-W will repeat the signals over lead 3|4W to repeater magnet ll of regenerative repeater 12 in Fig. 4 of the west terminal. The sequence switch 13E (Fig. 4) will, therefore, follow the position of sequence switch 36W while sequence switch 13W (Fig. 4) will follow the position of sequence switch 36E.

At station |0W (Fig. 5), a switch 32I is now provided which, when moved to the right, is placed in its transmitting position and when moved to the left, as shown, is placed in its receiving position. At this time contact tongue 26 will be in its downward position against its lower contact, since presumably s'tation |0W does not have slack tape when receiving signals from its companion station |0E. If station |0W is provided with slack tape and wishes to interrupt the transmission of signals from. |0E in orderto transmit signals to station |0E, a break key 322 is operated, which effects the transmission of a routing signal and enables sequence switches 36W and 13E to stop in the position to permit station |0W to now transmit to |0E. This would probably cause some gibberish printing upon receipt of the signals by receiver selector magnet 302 at station |0E. Under these conditions, the switch 32| at station IOE' should be moved to its receiving position; While the operator at station |0W is holding break key 322 depressed, switch 32| is moved to its transmitting position providing a circuit for start magnet, 21, and enabling station |0W to now transmit sig nals to |0E.

From the above description it is now apparent that signals may be transmitted in either direction between stations |0W, NW, and |2W and their companion or related stations |0E, IE, and |2E. Thus, for example, station |0W may transmit to station |0E while stations HE and |2E are transmitting to stations I |W and |2W. While the signals may be duplexed over the duplexing circuit 30| on a full duplex basis, transmission between the individual stations is on a half duplex basis, since the systemdoes not provide for simultaneous transmission in both directions between two related stations. v

Various changes and modifications may be made in the above described invention without departing from the spirit and scope thereof.

What is claimed is:

1. A telegraph system comprising a communication channel, a first plurality of stations each including a transmitting device for transmitting signals on said communication channel, a first sequencing device for sequentially connecting each of said stations to said channel for. the

transmission of asingle signal :codecombination, a second plurality of stations each including a receiving device and each related to one of said first mentioned stations for receiving signals therefrom, a second sequencing device :for sequentially connecting each of said second plurality of stations to said channel for receiving a single signal code combination from its related station, means automatically responsive to a change in the active or idle condition .of any of said first plurality of stations for conditioning said first sequencing device to connect only active stations to said channel for transmission, means for automatically generating a routing signal code combination whenever a change in the traific pattern occurs, and means responsive to the receipt of the individual impulses of said routing signal code combination for conditioning .said second sequencing device to connect only such of said second pluralityof stations to said channel which relate to active transmitting stations.

2. ,A divided channel telegraph system including a communication channel, a plurality of transmittingstations associated with one end of said channel, a plurality of receiving stations individually related to said transmitting stations and associated with the opposite end of said-channel, a first sequencing means associated with said transmitting stations, means automatically responsive to a, change in the active or idle condition of any of said transmitting stations for conditioning said sequencing .means to enable active transmitting stations to share transmitting time equally over said channel, means for automatically generating a routing signal code combination whenever a change in the trafilc pattern occurs, a second sequencing means associated with said receiving stations, and means responsive :to the individual signal elements of said routing signal code combination for conditioning said second sequencing means for selecting only receiving stations for operation which are related to active transmitting stations.

3. A station selecting system including a communication channel, a plurality of transmitting stations for transmitting signals over said channel, a sequencing device associated with said transmitting stations for determining their sequence of transmission, a plurality of receiving stations for receiving signals over said channel from related transmitting stations, means for transmitting a signal code combination indicative of the active condition of said transmitting stations, a single magnet selector responsive to the receipt of the individual impulses of said signal code combination, and a sequencing device controlled by said single magnet selector for sequentially associating receiving stations with said channel which relate to active transmitting stations.

4. A station selecting system, including a communication channel, a plurality of transmitting stations for transmitting signals over said channel, a first sequence device for sequentially associating said transmitting stations with said channel, a plurality of receiving stations for receiving signals over said channel from related transmitting stations, a second sequence device for sequentially associating said receiving stations with said channel, means for transmitting a signal code combination indicative of the active condition of said transmitting stations, a single magnet selector responsive to the receipt of said signal code combination, and a plurality of selecting elements operable by said single magnet selector in accord- 12 ance with said signal code combinations for conditioningsaid second sequence device for sequentially associating receiving stations with :said channel which relate to active transmitting stations.

5. In .a divided channel telegraph system, a single communication channel, a plurality-of stations located at one end of said channel, a plurality of stations located at the opposite end of said channel and individually related to said first mentioned stations,means including a duplex circuit for enabling transmission over said channel from one station to a related station in one direc tion while another station is transmitting over said channel in the opposite direction to its related station and sequencing devices at either end of said communication channel to control the sequence of transmission therefrom and to control the sequenceofreception thereat, whereby station relation may be maintained.

6. In a divided channel telegraph system, a single communication channel, a plurality of stations-located at one end of said channel, transmitting means and receiving means associated with each of said stations, a plurality of stations located at the opposite end of said channel and individually related to said first mentioned stations, transmitting means and receiving means associated with said second mentioned stations, means including a duplexing circuit for enabling the transmission of signals over said channel in one direction by the transmitting means of one station to the receiving means of a related station while the transmitting means of another startion is transmitting signals in the opposite direction over said channel to the receiving means 01 its related station and sequencing devices at either end of said communication channel to control the sequence of transmission therefrom and to control the sequence of reception thereat, whereby station relation may be maintained.

7. A divided channel telegraph system including a communication channel, a first plurality of stations each including a transmitting device for transmitting signals on said channel, a first sequencing device for sequentially connecting each of said stationsto said channel for transmission of a single signal code combination, a second plurality of stations each including a receiving device for receiving signals from a related first mentioned station, a second sequencing device for sequentially connecting each of said second plurality of stations to said channel for receiving a single code combination from its related station, means automatically responsive to a change in the active or idle condition of any of said first mentioned stations for conditioning said first sequencing device to connect only active stations to said channel for transmission, means for antomatically generating a routing signal code combination whenever a change in the traffic pattern occurs, and a single magnet selector responsive to the receipt of the individual impulses of the routing signal code combination for conditioning said second sequencing device to connect only such of said second plurality of stations to said channel which relate to actively transmitting stations.

8. A divided channel telegraph system including a communication channel, a first plurality of stations each including a transmitting device for transmitting signals on said channel, a first sequencing device for sequentially connecting each of said stations to said channel for transmission of a single signal code combination, a second pluralit'y' of stations each including-a receivingdevice for receiving signals'from a related firstmentioned station, a second sequencing device for sequentially connecting each of said second plurality of stations to said channel for receiving a single code combination from its related station, means automatically responsive to a change in the active or idle condition of any of said first mentioned stations for conditioning said first sequencing device to connect only active stations to said channel for transmission, means for automatically generating a routing signal code combination whenever a change in the trafiicpattern occurs, and a single magnet selector responsive to said routing signal code combination and including a plurality of selecting elements controlled thereby for conditioning said second sequencing device to connect only such of said second plurality of stations to said channel which relate to actively transmitting stations.

9. A divided channel telegraph system including a communication channel, a first group of stations each including a transmittin device for transmitting signals over said channel, a first sequencing device for periodically connecting each of said stations of said first group to said channel for transmission of a single signal code combination, a second group of stations each including a receiving device for receiving signals from a related station of said first group of stations, a second sequencing device for periodically connecting each station of said-second group of stations to said channel for receiving a single code combination from its related station, means automatically responsive to a change in the active or idle condition of any of said first group of stations for conditioning said first sequencing device to thereafter connect only active stations of said first group to said channel for transmission, auxiliary transmitting means for generating a conditioning signal and a routing signal whenever a change in the traffic pattern occurs, and a single magnet selector conditionable for operation on receipt of said conditioning signal and responsive to the receipt of said routing signal for conditioning said second sequencing device to thereafter periodically connect to said channel only such of said stations of said second group which are related to actively transmitting stations.

10. A telegraph system comprising a communication channel, a plurality of transmitting stations for transmitting signals over said channel, a sequencing device associated with said transmitting stations for determining their sequence of transmission, a plurality of receiving stations for receiving signals over said channel from related transmitting stations, means for periodically transmitting a routing signal code combination indicative of the active condition of said transmitting stations, a single magnet selector responsive to the receipt of the individual impulses of said routing signal code combination, and a sequencing device controlled by said single magnet selector for sequentially associating receiving stations with said channel which relate to active transmitting stations.

11. A station selecting system, including a communication channel, a plurality of transmitting stations for transmitting signals over said channel, a first sequence device for sequentially associating said transmitting stations with said channel, a plurality of receiving stations for receiving signals over said channel from related transmitting stations, a second sequence device for sequentially associating said receiving stations with said'channel, means for periodically transmitting a'signal code combination indicative of the active condition of said transmitting stations, a single magnet selector responsive to the receipt of said signal code combination, and a plurality of selecting elements operable by said single magnet selector in accordance with said signal code combinations for conditioning said second sequence device for sequentially associating receiving stations with said channel which relate to active transmitting stations.

12. In a telegraph system, a communication channel, a plurality of transmitting stations, a plurality of receiving stations for receiving signalsfrom individually related transmitting stations, a first sequence device having a stopping position for connecting each of said transmitting stations to said channel for transmission of a signal code combination and a stopping position for the transmission of a routing signal, means responsive to a change in the active transmitting stations for conditioning said first sequence device to stop in said routing position and to thereafter stop only at positions representative of active transmitting stations, a second sequence de-- vicehaving a stopping position for connecting each of said receiving stations to said channel for receiving a single signal code combination from a related transmitting station and a stopping position for receipt of a routing signal, control means for stopping said second sequence device in its routing position when a change in the traffic pattern occurs, and means for trans-' mitting a routing signal while both of said sequence devices are in their routing position to condition said second sequence device to thereafter stop only at positions which connect receiving stations to said channel which are related to active transmitting stations.

13. In a telegraph system, a communication channel, a first group of stations each equipped with transmitting and receiving devices, a second group of stations each equipped with transmitting and receiving devices, a pair of sequence devices for enabling the sequential transmission of single code combinations in one direction over said channel from each of the transmitting devices of said first group of stations to receiving devices of related stations of said second group of stations and a second pair of sequencing devices for' enabling the sequential transmission of single code combinations in the opposite direction over said channel from each of the transmitting devices of said second group of stations to receiving devices of related stations of said first group of stations, and means associated with said channel including a duplexing circuit for enabling the transmission of signals over said channel in one direction by the transmitting device of one station to the receiving device of a related station while the transmitting device of another station is transmitting signals in the opposite direction over said channel to the receiving device of its related station.

14. In a telegraph system, a communication channel, a first group of stations each equipped with transmitting and receiving devices, a second group of stations each equipped with transmitting and receiving devices, a pair of sequencing devices for enabling the sequential transmission of single code combinations in one direction over said channel from each of the transmitting de-' vices of said first group of stations to receiving devices of related stations of said second group of stations and a second pair of sequencing dew ideas for enabling the sequential transmission to! single code combinations in the opposite direc tion over said channel from each of the trans mittine devices of said second group of stations to receiving devices of related stations of said first group of stations, means responsive to a change in the active or idle conditions of th transmitting devices of said first roup oi ste tions for conditionin said first pair cfsequenc inc device to enable only active transmitting odevices of said first group of stations to transmit ignals to receiving devices of related stations f sa d second group of s a ions. means r sponsive to a change in the active or idle conditions oi the ransmi devices of said sec nd g oup of stations for conditioning said second pair oi sequencing devices to en ble only a t ve trans! mitting devices of said econd oup at stations o transmit ignals to receiving devices of related stations of said first group of stations, and means associated with said channel including a duple'xing circuit for enabling the transmission of signals over said channel in one direction by the transmitting device of on station to the receiving device of a related station while the transmitting device of another station is transmi ting Signals in the opposite dir ction over said ch nnel to the receiving device of its related station.

15. A telegraph system comprising a communication channel, a plurality oi transmit ing stations for transmitting signals over said channel a sequencing device associa e with said trans mitting tations for determining their sequence 01' transmission, a plurality of meivicr station: for receiving sicnals over said channel from related transmitting stations, means inoludinl to character oountina device for transmittine at regular intervals a rout ne signal code combination indicative of the active condition of said transmitting stations, a sm le magnet selector responsive to the receipt of the individual impulses of said routine signal code combination. and a sequeneine devi e controlled by said sinllo magnet select r for sequentially association: receiving stations with said chann l whichrelate to active transmittin at ifln MARTHA W. C. POTTS.

Eccentric Under the Las Will and Testament 0! Louis M. Potts. Deceased! REFERENCES CITED UNITED STATES PATENTS 228,828 Great Britain ml-c. Feb. 2, 1925 

